Method of flicker-free lighting hot-cathode low-pressure rare gas discharge lamp

Abstract

The present invention provides a method of lighting a hot-cathode type low-pressure rare gas discharge lamp without flicker. The method has the steps of operating, as a hot cathode, at least one of electrodes provided at both ends of a glass valve in a stable discharge state, and emitting light from a fluorescent material with the ultraviolet rays generated by the discharge of low-pressure rare gas sealed in the glass valve, or directly with visible light. The hot cathode is heated at least during lighting. In the method, the temperature of the hot cathode relative to the lamp current flowing between the electrodes is set within a region to prevent flicker in the discharge lamp.

What is claimed is: 
     
       1. A method of lighting a hot cathode low pressure rare gas discharge lamp including a glass tube containing a rare gas at a low pressure, and at least one cathode at an end of the glass tube, comprising: passing a current I L , in milliamperes, through the cathode in the glass tube of the discharge lamp and controlling a temperature T f  of the cathode so that when I L  is less than 55 milliamperes, T f , in degrees centigrade, is less than (6.5 I L  +592.5), and when I L  is at least 55 milliamperes, T f , in degrees centigrade, is less than (2 I L  +840) whereby flicker-free lighting of the discharge lamp is achieved.